Peter Francis, who was an undercover officer at the time, said the force was investigating Corbyn and nine other MPs. He said he was personally asked to collect information on the Labour leader.

The Telegraph also details Corbyn’s support for Balcombe Street, a notorious four-person gang within the IRA that waged a 14-month bombing campaign across England’s south-east. It also claimed Corbyn had links to the bomb maker believed to have been behind the Hyde Park and Regent’s Park bombings.

The aftermath of the Hyde Park bombings, carried out by the IRA, in July 1982 (Picture: Getty Images)

And the London Labour Briefing, a magazine of which Corbyn, John McDonnell and Diane Abbott sat on the board, was also being monitored by the security services.

One reader claiming to be an MI5 agent wrote to the magazine on its 25th anniversary, saying it had been their job for 25 years to monitor them.

A Corbyn spokesman said: ‘MI5 kept files on many peace and Labour movement campaigners at the time, including anti-Apartheid activists and trade unionists.’